Photocatalytic transformation of water pollutants into fuels

The exploitation of solar radiation in the remediation of organic water pollutants has the potential to be a sustainable energy source to replace fossil fuel. Conceptually, coupling H2 evolution and the degradation of organic pollutants through dual-functional TiO2 photocatalysis has been frequently nominated as one of the most sustainable and environmentally friendly technologies. However, the low quantum efficiencies achieved so far by using TiO2 photocatalysts, and the lack of a fundamental understanding of the reaction mechanism represent big challenges that need to be overcome before their potential can be fully realized. Despite the large number of studies every year that utilize the dual functional photocatalysis processes for the H2 production from simple water pollutants such as methanol, formaldehyde, and formic acid, aromatic pollutants, however, have been rarely considered. Thus, several open questions regarding the photocatalytic efficiencies and the reaction mechanism during the photoreforming of aromatic compounds still exist. In the presented work, the photocatalytic reforming of naphthalene in water has been investigated employing TiO2-based photocatalysts under solar irradiation. The effect of different crystalline phases of TiO2, namely Sachtleben Hombikat UV100 (pure anatase) and Evonik Aeroxide P25 (mixed phase of anatase and rutile), were assessed under the same experimental conditions. In order to understand the effect of Pt co-catalysts on H2 production, different fraction ratios were deposited on P25 and UV100. At the optimum loading ratio, 0.5 wt.% Pt-UV100 exhibited the higher photocatalytic activity toward the H2 formation and photooxidation of naphthalene comparing to all Pt-P25 samples. The observed decrease of the photocatalytic activity of the P25 after the platinization indicates that Pt nanoparticles act as a recombination center for the photogenerated charge carriers as revealed by electron paramagnetic spectroscopy techniques. Bes